Centralizer



Sept. 19, 1961 K. A. WRIGHT ETAL CENTRALIZER 2 Sheets-Sheet 1 Filed Nov. 5. 195'? United States Patent O 3,000,444 CENTRALIZER Kenneth A. Wright and James R. Solum, Los Angeles,

Caiif., assignors, by mesne assignments, to B and W,

ncorporated, Torrance, Caiif., a corporation of Caliorma Filed Nov. 5, 1957, Ser. No. 694,554 4 Claims. (Cl. 166-241) This invention relates to the well drilling and completion art and is particularly directed to improvements in a casing centralizer. Such devices are used to hold the casing in the center of the well hole during cementing operations. Casing centralizers of this type commonly comprise a pair of spaced collars which encircle the pipe, the collars being connected by a plurality of circumferentially spaced staves in the shape of bow springs which contact the bore of the well. The collars may be hinged to permit lateral application of the device in the casing.

It is an object of our invention to provide improved means for lattaching the ends of the staves to the annular collars. Another object is to provide lateral windows or openings on the collars through which the staves extend, together with skirts on the collars which overlap the end of the staves to confine them radially. Another object is to provide weld means in a novel location connecting the stave ends to the skirts, so that the weld metal is not materially stressed by exing of the bowed staves in service. Another object is to provide abutments on the collars adjacent the skirts which engage the extreme end faces of the staves. Another object is to provide lateral support for the stave ends by means of supporting engagement withvthe outer surface of the collars. Other and more detailed objects and advantages will appear hereinafter.

In the drawings:

FIGURE 1 shows a side elevation of a preferred embodiment of our invention.

FIGURE 2 is a. sectional detail taken substantially on the lines 2--2 as shown in FIGURE l.

FIGURE 3 is a sectional detail taken substantially on the lines 3-3 as shown in FIGURE 1.

FIGURE 4 is a sectional detail taken substantially on the lines 4 4 as shown in FIGURE 1.

FIGURE 5 is a side elevation partly broken away showing a modification.

FIGURE 6 is a sectional detail taken substantially on the lines 6 6 as shown in FIGURE 5.

FIGURE 7 is a sectional view taken substantially on the lines 7-7 as shown in FIGURE 5.

Referring to the drawings, the centralizer device ncludes a pair of spaced coaxial annular collars 10 connected by ya plurality of circumferentially spaced staves 11 in the form of bow springs. The collars are preferably of split construction and are duplicates. Each collar comprises a pair of semicircular ring segments 12 and 13 connected by hinges 14. The hinges on one collar are aligned with the hinges on the other so that the ring segments may be swung open -for lateral application to the casing 16, upon axial removal of aligned hinge pins 15 on the two collars.

Each of the ring segments is formed `from at sheet material and each is provided with a circumferentially extending outwardly directed protector rib 17. A smaller protector rib 18 of the same general shape may 'be located near the other end of each collar. The inner surface 19 of the ring segments is substantially cylindrical and lies closely adjacent the outer surface of the casing 16. The outer surface 20 of the ring segments between the protector ribs 17 and 18 is also cylindrical. This outer surface provides support for the straight end portions 2.1 of the staves 11.

3,000,444 Patented Sept. 19, 1961 ice A lateral window opening 22 is provided in the rin-g segments for each of the staves 11. In the particular construction shown in the drawings three staves 11 are mounted on each ring segment and accordingly, three Window openings 22 are provided. It will be understood that a greater or lesser number of window openings and staves may be employed if desired. The window openings 22 are formed in a portion of the outwardly extending lip 17 and the edge of the opening adjacent the rib is dened by a skirt 23, which overlaps the terminal part 27 of the stave 11 and confines it against outward movement. The under side of the rib 17 forms an abutment 24 which is contacted by the extreme ends of the staves. The protector rib 17 projects outward beyond the positions of the staves and hence the ends of the staves are not exposed to contact or hang up against any obstruction in the well bore. Y j

Weld means are provided for joining the extreme ends of the staves 11 to the collars 10 and as shown in the drawings, this means may take the form of a fusion weld 25 formed by depositing weld metal to join the extreme upper end face 26 with the inner surface of the skirt 23 and abutment 24. The location of the weld is such that flexing of the bowed staves in service does not develop any substantial stresses in the weld metal.

In the modified form of our invention shown in FIG- URES 5, 6 and 7, the collars 10a are similar to those previously described except that the skirts 23a extend downward substantially beyond the outline of the protector ribs 17a to form circumferentially spaced pockets 28 having side walls 29. The upper ends 21a of the staves 11a contact the outer surface of the collars 10a as described above and extend through window openings 22a into the pockets 28. The weld means 25a joins the skirt directly to the outer surface of the terminal part 27 of the stave 11a and this Weld means may take the form of a fusion plug weld or an electrical resistance projection Iweld. In either case the staves 11a are fully supported upon the outer surfaces of the collars 10a, as described above, and laterally braced by the pocket walls 29 and hence iiexing of the staves 11a in service does not act to subject the weld to any substantial stresses. In the same manner as the construction described above, the underside of the protector rib forms an abutment 24a limiting longitudinal movement of the staves 11a. The skirts 23a overlap and confine the ends of the staves 11a.

Having fully described our invention, it is to be understood that we do not wish to be limited to the details set forth herein, but our invention is of the full scope of the appended claims.

We claim:

1. In a casing centralizer, the combination of: a pair of spaced coaxial annular collars connected by a plurality of axially extending bowed staves, each collar having au internal abutment, circumferentially spaced axially extending skirts and side walls forming a plurality of pockets on each collar, each pocket having a window opening remote from said abtutment, each bowed stave having a portion supported on the outer surface of a collar and having a terminal part extending through one of said window openings between the side walls and into the corresponding pocket, respectively, the terminal part of each stave having an extreme end face and side faces and being confined and overlapped by its respective skirt, the extreme end face of each stave engaging said abutment and the side faces engaging said walls, and weld means joining each stave to said collar.

2. The combination defined in claim 1 in which the weld means joins the overlapping portions of each stave and skirt.

3. In a casing centralizer, the combination of: a pair of spaced coaxial annular collars connected by a plurality of axially extending bowed staves, each collar comprisinga pair of semi-circular ring segments connected by a hinge and a diametrically opposed latch, the hinge on oneannular collar being aligned with the hinge on the other to permit the ring segments to be swung open for lateral. applicationV tothe'casing, each ring segment havingV an internal abutment, circumferentially spacedy axially extending skirts and side walls forming a plurality of pockets on eachl collar, each pocket having ,aV windowopening remote from said abutment, each bowed stave having a portion supported upon the outer surface of the collar and a terminal part extending through one of said` window openings between the side walls and into the corresponding pocket, respectively, the terminal part of each stave having extreme end facel and side faces and ing an internal abutment, circumferentially spaced, skirts and side walls onthe collar extending axially from the protector rib and a plurality of pockets, each pocket having a window opening remote from said abutment, each end portion of each bowed stave contacting the outer surface of one 0f the collarsl for lateral support and having aterminal part extending through one of said window openings between the side walls and into the corresponding pocket, each terminal part having an extreme end face and side faces and being conined and overlapped by the rib and skirt on one of said collars, the extreme end faces of each stave engaging said abutments and the side faces engaging said walls, and weld means joining the staves to said skirts.

References Citedl in the lile of this patent UNITED STATES PATENTS 1,775,376 Steps et al. Sept. 9, 1930 22,311,768 McCrayy Feb. 23, 1943 2,605,844 Clark Aug. 5, 1952 2,640,544 Baker Iune'Z, 1953 2,680,488 Y Atkinson June 8, 1954 2,727,576 Hall Dec. 20, 1955 2,845,128 Clark July 29, 1958 

